RELATION OF ORGANIC CONSTITUENTS. 23 



tion has been called to the fact that citric, malic, oxalic, and acetic 

 acids in combination with potash exert a very favorable influence 

 on the burning qualities. It was found by direct experiment that 

 these acids in the free state injure these qualities, but as they 

 probabl}'^ never occur free in fermented tobacco this fact is of little 

 consequence. Citric and malic acids are undoubtedly of fundamental 

 importance in producing good burning qualities, but since oxalic 

 acid occurs in combination with lime and not with potash in tobacco 

 it is of little value in this respect. Pectin and the pectoses are 

 present in considerable (juantities in cured tobacco leaves, but, accord- 

 ing to Schlosing, these are all converted into pectic acid during the 

 process of fermentation. xV sami)le of pectic acid jDrepared from 

 fermented tobacco was found to produce no injury to the fire-holding 

 capacity; in fact, when combined with potash it acted favorably on 

 this property. 



According to Kissling, the tobacco tars, consisting of a mixture 

 of a number of chemical individuals, exert an important influence 

 on the quality of the i)roduct. Some of these are of an acid charac- 

 ter, while others are indifferent, substances. When tobacco is ex- 

 tracted with large volumes of water, as previously described, con- 

 siderable quantities of these tariy acids combined with nicotine and 

 other bases pass into solution, and on evaporation of the extract 

 the salts are decomposed, the nicotine volatilizing and the tarry 

 acids being precijDitated. These acids in the free state were found 

 to be decidedly injurious to the burning qualities, but they occur 

 in tobacco in comparatively small quantities. 



A number of samples of tobacco of very poor burning quality were 

 extracted with alcohol to determine if this solvent would remove 

 any constituents deleterious to the burn, but with the exception of a 

 single case this treatment did not improve the tobacco in this respect. 

 The constituents removed by extraction with alcohol are nicotine 

 combined with acids, tannic acid, glucosides, sugars, and the tars and 

 tarry acids; hence it appears that none of these compounds ^re of 

 special importance with reference to the burn. Direct experiments 

 showed that glucose does not materially influence the burning quali- 

 ties. Nicotine is the characteristic alkaloid of tobacco and is of great 

 importance with reference to its physiological action, but its salts 

 were found to have no effect on the burn. In addition to nicotine the 

 important nitrogenous constituents are the amido compounds and the 

 albuminoids. It is generally believed that the amido compounds 

 exert a favorable and the albuminoids an unfavorable influence on 

 the desirable qualities of tobacco, including the burn, although there is 

 little experimental proof of this theory. The quantity of plant wax 

 occurring in tobacco is too small to affect the burning qualities. 



105 



